Dr. Dawley's Press Conference

David Rogers

To many people, salamanders are no more than slimy creatures that crawl around on four legs. But to Dr. Ellen Dawley, they display many mysterious chemical interactions. On Nov. 14, Dawley came to the Myrin Library at Ursinus College to speak about her research on the red backed salamander.

                According to Dr. Dawley, salamanders are very territorial vertebrates that use a process called chemosensation to interact with each other. During chemosensation, the salamanders use chemoreceptor cells to facilitate mating, social interactions and territorial displays of dominance. In Dr. Dawley’s research she noticed that salamanders experience an up-regulation of chemoreceptor cell proliferation in late spring compared to other seasons. The question she investigated is how long do these chemoreceptors generated in late spring survive and are they able to function as receptor cells?

                In order to conduct her experiment, Dr. Dawley collected red backed salamanders from Montgomery County, MD in May and June. The salamanders were injected with a solution called BrdU which is used to mark the birthdate of vomeronasal epithelial cells. The salamanders were kept separate in petri dishes, and then eventually killed and dissected. They were separated into different sections in order to identify which sections of the body generated the most epithelial cells.

                Dr. Dawlye found that many of the new cells generated were in fact receptor cells. Much of the BrdU cells found were vomeronasal receptor cells that were born in May, and could become functional in the summer. These cells, which were born in late spring, remained viable throughout the summer and into the fall. These results support her supposition that the salamander has specific behaviors during the summer that rely on chemoreception.

                Salamanders are used to moist areas, so the warm, dry days of summer present a challenge to the salamander when searching for valuable territory. Because of this, they are very aggressive and territorial during the summer. Territories with more access to food are guarded much more aggressively, and the most aggressive territorial salamanders are therefore much larger.

                The salamanders also use their smelling capabilities to assist them in the summer.

                “They can gauge the quality of a territory using chemosensory,” Dr. Dawley said.

                Additionally, males use fecal pellets to advertise the foraging quality of their territory. Female salamanders smell the fecal matter and are able to use chemosensory to identify the quality of food in the territory. This suggests that chemosensory during the summer assists territorial process as well as mating processes.

                Very few other animals have shown to up-regulate the proliferation of chemoreceptor cells during seasonal periods. Dr. Dawley’s findings are unique and will hopefully lead to more practical applications in humans and other animals. If a similar process of up-regulation could be applied to humans, the human body could possibly create solutions to brain damage and other tissue damage. This is an idea that may be far in the future, but Dr. Dawley may have helped initiate the process.